TONIGHT: Helgenberger checks out of CSI

Wednesday is Marg Helgenberger’s last day on CSI: Crime Scene Investigation. After 12 seasons and over 250 episodes, the 52-year-old actress is the latest to leave the long-running forensic crime drama. Her final episode is entitled, “Willows in the Wind” (10 p.m., CTV and CBS).Helgenberger is leaving to open a string of fast food restaurants. They will feature the “Helgenburger,” a double stacked patty with or without dressing.Actually, no, I just made that up. For more on Helgenberger’s departure, read this story I wrote which appears in today’s Toronto Star.Hour-long dramas are a marathon, with eight day per episode schedules and plenty of long days in and out of trailers. Still, is leaving a hit show a smart move? I remember years ago asking William Devane why, after eight or nine seasons, he was still doing Knots Landing. I’ll never forget his answer: “Never get off the gravy train until the gravy train stops running.”Still, hats off to Helgenberger, always a friendly face at TCA press tours. Earlier this week, she received her own star on the Hollywood Walk of Fame.